It is known to provide a mid-turbine frame assembly between high and low pressure turbine (HPT and LPT) rotors to support bearings and to transfer loads radially outwardly to a core engine casing. The mid-turbine frame assembly typically comprises a mid-turbine frame supporting an annular inter-turbine duct therein. The inter-turbine duct is defined between outer and inner duct walls which are interconnected by a plurality of radial hollow struts, thereby forming an annular hot gas path to convey the working fluid from the HPT to the LPT. The inter-turbine duct and the hollow struts are subjected to high temperatures and therefore cooling air is typically introduced around the inter-turbine duct and into the hollow struts to cool the same. A portion of the cooling air supplied to the mid-turbine frame may also be used to cool the LPT rotor. However, as the air travels through the mid-turbine frame, the air picks up heat. As a result, the air available for cooling the LPT rotor is not as cool as it could be. This may have a detrimental effect on the integrity and durability of the LPT rotor.
There is thus room for improvement.